1. Field of the Invention
The present invention relates to compositions comprising one or more enzymes and one or more surfactants, useful in the cleaning of industrial and non-industrial equipment. The present invention further relates to novel cleaning methods using surfactants and enzymes to remove oil, grease and other hydrophobic and/or industrial wastes from various surfaces. One method involves cleaning the surface by contacting it with a composition comprising one or more enzymes and one or more surfactants. A second method involves sequentially contacting of the surface first with a surfactant-containing solution and then with an enzyme-containing solution.
2. Background Information
The equipment used in numerous industries comes into contact with various contaminants, which can impede the operation of the equipment and otherwise interfere with production. This effects nearly every industry, including, for example, the chemical processing industry, the oil refinery industry, the pulp and paper industry, the general manufacturing industry, and the food and beverage industry. Numerous ferrous and non-ferrous metal surfaces, as well as plastic surfaces, can similarly become contaminated with oils, greases and other hydrophobic contaminants, as well as inorganic contaminants such as soil. These contaminants are often difficult and expensive to remove using conventional cleaning products and methods. A cleaning step is also routinely included in metal and plastic surface finishing. Typically, these surfaces are cleaned before phosphatizing, rust proofing, painting and the like is done to the surface.
Many aqueous industrial and household cleaners contain a mixture of enzymes and surfactants. The enzymes primarily serve to attack or degrade organics, while the surfactant acts to disperse the degraded particles in the aqueous phase.
Numerous cleaning compositions have alkaline components, such as a caustic, an alkali or an alkaline metal cation. For example, an alkaline based cleaning composition is disclosed in U.S. Pat. No. 5,256,327. More specifically, the cleaning composition is a substantially dry, water soluble dishwashing composition comprising intimately admixed particles of a carbonate salt and a citrate where the salts have a common alkaline metal cation, an anti-redeposition agent, an alkaline metal silicate, a nonionic surfactant, and an enzyme system. Alkaline cleaners, although effective, are considered environmentally unfriendly with harsh or hazardous effects and are therefore not preferred.
U.S. Pat. No. 4,784,790 relates to preparations and processes for cleaning and disinfecting endoscopes. The method includes successively contacting the endoscopes with a heated cleaning solution, contacting the endoscopes with a heated disinfectant solution, washing the endoscopes with heated water and drying the endoscopes with sterilized hot air. The cleaning solution contains at least one low-foam nonionic surfactant, at least one proteolytic enzyme, at least one complexing agent and, optionally, other standard detergent ingredients, and has a pH value of 6 to 8.
U.S. Pat. No. 5,234,832 discloses a method for cleaning and disinfecting medical instruments similar to that in U.S. Pat. No. 4,784,790 but utilizing a cleaning solution having a pH of from 6 to 8 and containing a low-foam nonionic surfactant, a proteolytic enzyme, a complexing agent, and an aldehyde selected from the group consisting of formaldehyde and aliphatic dialdehydes containing 2 to 8 carbon atoms and, optionally, other standard detergent and disinfectant constituents. This method further differs from the '790 patent in that it does not include the disinfecting step.
U.S. Pat. No. 5,462,607 relates to a method of removing hydrocarbons and coke deposits from industrial processing equipment. The method involves use of an aqueous cleaning solution containing from 30 to 2500 ppm of an amine oxide surfactant and 1 to 200 ppm of an enzyme. The method further involves introducing the cleaning solution into a vessel having hydrocarbons and coke deposits on its walls, partially filling the vessel, heating the solution in the vessel to an elevated temperature sufficient to ebullate the solution and generate foam, circulating the heated solution through the vessel and flowing the foam from the vessel.
U.S. Pat. No. 5,540,784 similarly relates to a method for cleaning equipment containing solids and oil contaminants on an interior surface by creating a closed-flow system within the equipment, introducing an aqueous cleaning solution containing enzymes and an amide oxide surfactant to a pressure vessel in the system to partially fill the vessel, heating the cleaning solution to a temperature above the boiling point of water, circulating the cleaning solution through the system, thereby bringing the cleaning solution into contact with the oil and solid contaminants and removing the contaminants. A pressure is maintained within the closed flow system at a value above atmospheric pressure. The cleaning solution contains 30 to 2100 ppm of a surfactant and 1 to 200 ppm of an enzyme.
U.S. Pat. No. 5,459,066 relates to a method of separating oleophilic-hydrophobic material from wash water. The methods employ a solution comprising 30-2100 ppm of an amide oxide surfactant and 1-200 ppm of an enzyme. The solution is mixed with wash water and oil and allowed to stand in a quiescent state for a time sufficient for the formation of an oil phase and an aqueous phase. The oil phase is then separated from the aqueous phase.
U.S. Pat. No. 5,538,664 discloses a hard surface detergent composition comprising a nonionic detergent surfactant, a hydrophobic cleaning solvent, and optionally containing one or more of polycarboxylate detergent builders, zwitterionic detergent surfactants, alkanolamine pH buffer, enzymes, hydrotropes, polar solvents, colorants, perfumes and a suds control system comprising fatty acid and anionic sulfonated and/or sulfate detergent surfactant.
German Abstract DE 1801119 discloses a detergent and soap powder containing a bleaching agent and an enzyme prepared by coating or encapsulating the bleaching agent with a water insoluble material dispersible in water at a temperature between 60 and 70.degree.. A proteolytic enzyme is coated with a water soluble material such as sugar, a nonionic surfactant, CM-cellulose gum, or polyvinyl alcohol.
Patent Application WO 9412607 relates to a hard surface cleaning composition comprising a solvent, surfactant and a lipolytic enzyme. The solvent contains at least one alcoholic hydroxyl group and one ether linkage and is essential for the performance of the cleaning composition. The surfactant is compatible with the lipase.
German Abstract DE 3640799 discloses a washing composition containing at least one amino or hydroxy alkane sulphonate derivative and at least one enzyme. There is no indication that the abstract teaches the compositions or methods of the present invention.
International Application WO 9633257 discloses a stabilized enzyme-based cleaning solution containing an enzyme, including a lipase or protease, a surfactant and glycerol and/or ethylene glycol as an enzyme stabilizer.
Japanese Abstract JP 4214884 discloses a cleaner for noble metals and ornaments containing carbonate, organic acid, reducing agent, surfactant and protease.
Japanese Abstract JP 8188893 discloses a cleaning agent containing a fat-decomposing enzyme and a non-ionic surfactant at a ratio of 100:1-1:100 and a pH of 6.5-10.
German Abstract DE 2753679 discloses a stable aqueous washing and cleaning composition containing catalase, an anionic surfactant and a nonionic polygonal ether derivative surfactant.
None of the above references teach a cleaning composition comprising at least one nonionic surfactant and at least one enzyme as taught by the present invention. Nor do any of these references teach a method for cleaning metal or plastic surfaces comprising contacting the surface to be cleaned with this composition, or by contacting the surface to be cleaned with a first solution containing a nonionic surfactant, and then contacting the surface with a second solution containing an enzyme. There remains a need, therefore, for cleaning compositions and methods that are efficient, cost effective, biodegradable and otherwise friendly to the environment.